Diplomats say the European Union has moved closer to starting membership talks with Serbia, but said any further progress will depend on Serbia's full cooperation with the UN war crimes tribunal.

EU foreign ministers meeting in Luxembourg today agreed to ask the bloc's executive commission for an opinion on whether to launch entry talks with Serbia, according to diplomats.

The move is a first step in the long accession process.

But at the same time, the ministers said that any further steps in the accession process would require that all EU member states unanimously decide that Serbia was cooperating fully with the International Criminal Tribunal for the former Yugoslavia (ICTY).

The Netherlands had been concerned that by moving forward on Serbia's membership bid, the EU would lose leverage to press the hunt for fugitive indicted war criminals, including former Bosnian Serb military commander Ratko Mladic.

The meeting comes after Serbia and Kosovo agreed in September to an EU-brokered dialogue to resolve outstanding issues, although Serbia has not recognized Kosovo's independence.

"We've been engaged with Serbia and with Kosovo in moving forward on discussion, and I hope those will start very soon," said EU foreign-policy chief Catherine Ashton, speaking as she arrived for the meeting, "and I am extremely pleased that [Serbian] President [Boris] Tadic and [Kosovo's] Prime Minister [Hashim] Thaci have really taken the spirit of this and want to move forward."

On the sidelines of today's meeting, Bozidar Djelic, Serbia's European affairs minister, pledged that his government would "do everything in its capacity to find and extradite" Mladic.